Dr. Donndelinger and coworker have observed an interesting phenomena in high resolution microscopy of thin tissue sections: 'light' and 'dark' cells in the sections. There appears to be some degree or regularity in the occurrence of the two types of cells, with obvious differences in daughter cells where one is light and the mate is dark. Dr. Donndelinger presented a seminar at the NFCR in which he described his results. We are exploring whether it is feasible to flow sort "light" from "dark" cells with the goal of determining whether there are any genetic differences between the two types. As a first step, we have sent him a sample of fixed multicellular spheroids that he is examining to see of the phenomenon is present. If it is, we will explore whether the sorting experiments should be pursued.